1. Field of the Invention
The present invention relates to a DC/AC inverting circuit, and in particular relates to a controller applied in a DC/AC inverting circuit.
2. Description of the Related Art
Liquid crystal displays (LCDs) are thinner and occupy less space than a conventional cathode ray tube (CRT) displays. LCDs are applied in household televisions and public signboards. LCDs display images and text by optical rotation of liquid crystal materials and electronic optics. Since a panel of an LCD device is not able to light itself, an additional backlight source is used to assist in emitting light. Fluorescent lamps typically serve as the backlight.
A DC/AC driving circuit is used to drive the fluorescent lamps and is usually referred as an inverter. The DC/AC driving circuit always uses a constant frequency for backlight of the LCD to reduce interference. The invention provides a control method for determining an operational frequency according the states of the fluorescent lamps, simplifying the design of the inverter.